Search Documents

By Alex C. Smith, Thomas P. Mucho, John B. Walsh, Alden Ozment, Michael R. Thibou, Michael A. Trevits

The National Institute for Occupational Safety and Health (NIOSH), with US Foam Technologies, Inc. and On Site Gas Systems, Inc., conducted research on the remote application of extinguishing agents with the intent of improving deployment strategies to limit miner exposure and to help ensure the best possible outcome during a mine fire. Full-scale in-mine were conducted at the NIOSH Lake Lynn Experimental Mine to determine the flow characteristics, stability and fire-suppression capability of gas-enhanced foam. The in-mine experimental work was designed to evaluate movement of gas-enhanced foam through mine workings closely simulating an underground coal mine environment and how long gas-enhanced foam would remain stable. This paper presents results of the experiments and provides valuable insight into mine fire deployment strategies for gas-enhanced foam technology.

By E. W. Codington

The pebble-phosphates of Florida occur in a district roughly bounded on the north by the 28th parallel, on the east by an irregular line running a few miles east of Peace river and on the west by the Gulf of Mexico, and covering an area of about 4000 square miles. There seems to be no reason why the deposits should not extend farther south along the gulf coast. That section remains unprospected, transportation-facilities being non-existent. It is not intended in this paper to discuss the geology of these formations; but a word as to their probable origin will be perhaps the best method of giving a correct idea of their present position. Starting with a low, flat surface, with even less of superficial undulation than appears at present, an im-

Jan 1, 1896

By Seedsman R. W

Good roads are essential in moving men and materials to and from the underground workplace. Coffey Partners International Pty Ltd (Coffey) has recently completed a underground coal industry funded project on underground mine road construction and maintenance. This paper discusses practical approaches to construction and maintenance of underground mine roads using transferrable civil technologies and innovative techniques. Mine pavements are generally low-cost (relative to civil roads), constructed to varying standards using locally available materials to best meet the mobility needs of the mine. Performance of pavements is thus largely dependent on the environmental conditions, quality of the available road making materials, maintenance policies and available resources. The paper will detail `what causes bad roads?' in various underground environments, available management strategies, construction and water control techniques, road maintenance and vehicle considerations.

Jan 1, 1995

By Nicholas M. Short

Many a geologist or driller has wished he could somehow climb into a borehole to see for himself what fractures looked like. Or why recovery was poor. Or how the bit was actually lost. Now it is possible to do the next best thing to climbing into the hole. TV cameras are being used for a close-up look at borehole conditions. Ever since television was invented, geologists and others interested in subsurface conditions have wanted a TV camera that could be used in the narrow confines of a borehole. But development of such a camera was slow, mainly because of the need for compact size. Not until the late 1950's did the technology of electronic miniaturization develop to a point where a camera satisfactory for the purpose could be put together.

Jan 1, 1963

By Jacques Deraisme

Geostatistics has been applied in many mining feasibility studies throughout the world during the last decade. Recently geostatistics has begun to be applied to the field of mining processes by attempting to aid in the definition of the best mining policy. For a feasibility study the grade-tonnage relationships give a reasonable order of magnitude estimate of the ore reserves within the deposit. But the reserves that will actually be recovered, will vary depending upon the mining methods and the technical means used. The profit earning capacity of the mining project is determined by a great many factors, such as for instance: accessibility of reserves to extracting machines, the haulage distance between the mine and the mill, the variability of produced ore (tonnage and grades) which could necessitate stockpiles or blending areas?

Jan 1, 1979

By C. A. Hansen

INTRODUCTION It has been the experience of the writer, during some. five years' work with electrolytic zinc, that the zinc cell is perhaps more- sensitive to impurities in the electrolyte than the analytical methods as yet developed for the chemical identification and determination of these impurities; but that, when proper purification methods have been applied to a given solution, the behavior of the cell is quite independent of the original sources from which the zinc sulphate has been derived. It has also appeared that the behavior of the zinc cell is the best and surest check on the correctness and thoroughness of the purification methods used, because it indicates the presence of both current impurities. and cumulative impurities derived from the leaching of the ore; it also in

Jan 3, 1918

By Terry Aben

Outline ?Review of standards that can be used to identify current coating conditions and optimal points to perform coating maintenance. ?Identify how standards can be used to extrapolate the future condition of coatings to achieve predictive maintenance planning. ?Demonstrate how the above can be combined with project estimating to generate a data driven, quantitative, predictive, risk-based asset integrity maintenance program for Protective Coatings. The Value of Asset Integrity Programs ?Maximize the benefit produced from the investment in maintenance spending. ?Get the best bang for your buck! ?Don?t perform maintenance work before it is necessary ?Money is invested early with no increase in the service life extension. ?Don?t delay until it is too late. ?Planned Maintenance is far less costly than Reactive Maintenance. ?Identify the Optimal Point for Maintenance.

Nov 1, 2011

By A. B. Whitehead

A spectrographic method for the determination of 18 impurities in cerium is presented. The carrier distillation technique is utilized to separate the spectra of impurities from the complex spectrum of cerium. Metal samples are ignited to the oxide, mixed with silver chloride carrier containing an internal standard, and excited with a 20-ampere direct-current arc. An additional exposure, made after carrier depletion, provides for the determination of refractory elements. Experiments to determine the best carrier, sample-carrier ratio, electrodes, arc current, exposure conditions, internal standards, and any matrix effect are described. The relative standard deviation of the method at the 20- and 200-part-per-million levels is about 25 and 15 percent, respectively. The average relative error is about 20 percent in the 10- to 1,000-part-per-million concentration range.

Jan 1, 1962

By A Galli

Traditionally pit optimisation and scheduling is carried out assuming that the resources, the commodity prices and production costs are all known. Once the pit contour and the mining schedule have been determined, geostatistical simulations can be used to assess the impact of the uncertainty in the resources on the pit design and the schedule, and likewise stochastic simulations can be used to test its robustness to fluctuations in costs and prices. But it would be more interesting to have a dynamic procedure for optimising the pit as the resources become better known and as economic factors such as commodity prices and costs evolve over time. This paper presents a novel approach for doing this. Rather than working with millions of small selective mining units, it was decided to work with large blocks, called macro-blocks. Mining sequences are defined as the quantities to be extracted from each macro-block in each time period. Feasible mining sequences are mining sequences that respect the accessibility constraints, and also the geometric constraints on the amounts that can be extracted from any one block over time, or from all the active blocks at a given time. Having defined feasible mining sequences, their mathematical properties were studied. It was found that natural breakpoints occur in the sequences when one set of blocks have been completely mined out, thereby opening up access to others. It was discovered that families of sequences exist, and that they are convex and closed under certain types of row permutation operations. Convexity is an advantage when optimising. The closure property opens up the possibility of mixing and matching subsequences of rows in the sequences. Another interesting property is that the sequences form branching families, rather like the binomial and trinomial trees used to model prices in finance and in real options.It is easy to generate large numbers of feasible mining sequences randomly. A two-step procedure is used to find the best one (or the best few) using three economic criteria: expected NPV,the probability of a negative NPV, and the percentage of years when the cash flow is negative. The procedure was tested on a synthetic gold mine based on the characteristics of the Essakane mine in Burkina Faso. The results were encouraging.

Sep 26, 2011

By R. W. Raymond

THE question, what is the best proportion among weight, fall, and speed of stamps, is one which has not yet received thorough and systematic examination. In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally, the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such conditions as weight and lift of stamps, and only within narrow limits for their speed. We may eliminate of friction, transmission, and generation of power, in the case of stamps, by measuring the power actually developed by their fall. Thus, the weight, multiplied into the fall in feet, and the number of drops per minute, gives us exactly the number of foot-pounds exerted by each stamp. Dividing by 33,000, the number of foot-pounds per minute in one-horse power, we have the horse-power per stamp, from which the effective power of the whole mill may be obtained. Dividing the amount of rock crushed daily by the effective horse-power, gives us the daily amount per horse-power ; and this is the best measure that can be obtained for the effectiveness of the stamps. A complete discussion of the subject would require us to determine the exact influence of the discharge, etc., and the exact resistance offered by different classes of rocks, for both of which points the data are wanting. Professor J. D. Hague, in the third volume of the United States Geological Exploration of the Fortieth Parallel, gives a valuable

By H. C. Otis

DURING the past year or two considerable time and money have been spent in developing equipment for tubing large-volume high-pressure oil and gas wells without loss of production. That the efforts have met with success is proved by the fact that any properly cased well, regardless of its production or regardless of its rock pressure or working pressure, can now be safely tubed with no appreciable loss of production, provided experienced crews handle the new equipment. It is conceded that a far better gas-oil ratio can be secured by flowing a well through tubing of a proper diameter-the diameter of the tubing depending, of course, upon the volume of fluid and gas and the depth of the well-than by the more usual method of installing a choke at the mouth of the well. Where possible it is becoming the practice to bring wells in through tubing, though in the majority of instances this is not feasible. In many instances it has developed, after a well has been brought in through tubing, that the tubing installed is either too large or too small for the most efficient operation or that the well had not been drilled deep enough. The equipment described in this paper, in the hands of experienced men, permits the tubing of these wells after they have been brought in, with the size of tubing then determined by actual observation to be best suited for each particular well, and with no danger of the well getting out of control, of catching fire, of drilling itself deeper, or of any loss of production. The deeper the flowing production with the consequent future higher lifting costs, the more essential it is that the size of tubing used be such as to give the best possible gas-oil ratio. The ability to bring in these deep wells through the casing and then, immediately after their completion, regardless of volume or pressure, to tube them with the size of tubing that permits the most efficient use of the gas present will doubtless save many dollars.

Jan 1, 1929

By R. W. Raymond

THE question, what is the best proportion among weight, fall, and speed of stamps, is one which has not yet received thorough and systematic examination. In considering the economical application of stamping machinery, we meet, at the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally, the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such conditions as weight and lift of stamps, and only within narrow limits for their speed. We may eliminate questions of friction, transmission, and generation of power, in the case of stamps, by measuring the power actually developed by their fall. Thus, the weight, multiplied into the fall in feet, and the number of drops per minute, gives us exactly the number of foot-pounds exerted by each stamp. Dividing by 33,000, the number of foot-pounds per minute in one-horse power, we have the horse-power per stamp, from which the effective power of the whole mill may be obtained. Dividing the amount of rock crushed daily by the effective horse-power, gives us the daily amount per horse-power; and this is the best measure that can be obtained for the effectiveness of the stamps. A complete discussion of the subject would require us to determine the exact influence of the discharge, etc., and the exact resistance offered by different classes of rocks, for both of which points the data are wanting. Professor J. D. Hague, in the third volume of the United States Geological Exploration of the Fortieth Parallel, gives a valuable

Jan 1, 1873

By W. B. Collingwood, D. Misra, T. Ghosh, S. Bandopadhyay

Understanding the variability of sulfur and calorific value in coal seams is critical to planning mining operations and marketing the mined coal. In this study, statistical and geostatistical techniques were used to explore the underlying spatial trends present in a large coal deposit. Eight prediction models for the sulfur content of the coal seam were developed. Six of the models were created using geostatistical techniques, while the remaining two models were created using other techniques. The performance of each model was examined by conducting cross validation exercises. The results of the study showed that very pronounced trends and anisotropies were present in the sample data, which had to be accounted for in the modeling. The study found that a cokriging model using sulfur and ash is the best prediction model for predicting sulfur content in this coal reserve.

Jan 1, 2014

Simulation and Analysis of Media Behaviour in the Tower Mill by Discrete Element Method for Estimating the Power Draw and Spatial Distribution of Grinding Process The trends to the Tower Mill (TM) for grinding the materials are increased recently due to its unique merits. Among the various considerations of this machine, the main important items are increasing the efficiency of grinding as more as possible while keep the power consumption, manufacturing and maintenance costs as less as possible. Because this grinding process includes a huge numbers of media particles (ball or other shapes) that are interacted with each other and body of the machine, the DEM (Discrete Element Method) way is a very useful and essential step to getting confident evaluations. Because the DEM simulation is a very young scientific field and proper commercial software are very rare and still under modification, at first step, a FORTRAN code is developed for DEM simulation of two laboratory Tower Mill models (KM5 and KD5). The simulation and experimental results matched each other properly. Then one another DEM software was implemented to perform simulation of bigger models (huge numbers of balls), meanwhile could handle the complex 3D geometry data. The simulation and experimental results were compared and analysed in detail for not only laboratory but also for industrial models (KW5, KWD5, KWD50, KW300F, KW700F and KW1500) without any manipulation or compromising of the parameters of simulation. Some numeric data of industrial models are hidden here due to confidential reasons. The relative velocity of balls (ball-ball and ball-TM body), dissipate energy, interacted forces and stresses during the process are the key outputs of DEM simulation for design this machine. Therefore the main important processes in a Tower Mill machine are recognised and consequently some horizons of development of this machine are distinguished.

Sep 13, 2010

By A. J. Jager, J. A. Ryder, M. U. Ozbay

This paper deals with procedures used for designing pillar systems in hard-rock tabular mines operating at shallow depths, typically less than 1000 m. A comprehensive review if current practice identifies four types if pillars, namely non-yield, yield, crush and barrier pillars, and the main principles for designing these pillars are outlined. It is shown that the current design methods for pillar systems in South Africa are mainly empirical, each mine developing its pillar-design methods based largely on practical experience. This results in varying pillar layouts, even between neighbouring mines, despite similarities in geology, and depth if mining. It is suggested that some current layouts may fall short if being the best as regards safety, the maximum safe extraction percentages, or flexibility in accommodating future mining scenarios in deeper or otherwise different geological conditions.

Jan 1, 1995

By Harold J. Miller

Loading and haulage of run-of-mine ore is frequently the highest cost in underground mining operations. These costs can be significantly reduced by use of belt conveyors, a common practice in coal and similar soft miner ii mines. This is particularly true if oversize ore and rock can he eliminated prior to conveying; thus producing a demand for crushers near the production areas. Portable feeder-breakers are extensively used in conveyorized mines, but no suitable, equivalent equipment, is available to provide these benefits to hard rock mines of low to medium headroom. A hard rock crusher capable of easy movement and readily disassembled would allow use to belt conveyors and could improve the general safety and productivity of any underground ore hauling system. This report summarizes proposals and findings made in conjunction with the newly designed M-44 Low Head Portable Crusher which is believed well capable of meeting the requirements of a "portable, underground, hard rock" machine as previously defined in earlier reports. Data gathered by use of the 1/4 Scale Model of the M-44 has substantiated and verified the concept sufficiently to justify construction of a full-size machine for further testing under actual mine conditions.

Jan 1, 1978

By Sam S. Taylor

Disposal of brines produced with crude petroleum and natural gas is a continually increasing problem. The necessity for studying this problem has been realized more generally in recent years, and in August 1934 an agreement was made between the Kansas State Board of Health and the United States Bureau of Mines to conduct a cooperative technical study of methods of brine disposal. To date one paper in the technical press4/ and three reports5/6/ have been published in which are given results of studies carried on under this cooperative agreement. In the Mid-Continent fields, the methods used most generally for handling oil-field brines are: (1) Impounding in evaporation ponds; (2) controlled diversion into surface streams; and (3) injection into subsurface formations through wells assigned for this purpose. Various States recognize one or more of the methods as legally authorized procedure. Impounding brine in ponds and solar evaporation have proved inadequate as a general rule, owing, usually, to the porous nature of the soil, the low rate of evaporation, or both. Diversion, of

Jan 1, 1937

By Sam S. Taylor

Disposal of brines produced with crude petroleum and natural gas is a continually increasing problem. The necessity for studying this problem has been realized more generally in recent years, and in August 1934 an agreement was made between the Kansas State Board of Health and the United States Bureau of Mines to conduct a cooperative technical study of methods of brine disposal. To date one paper in the technical press4/ and three reports5/6/ 7/ have been published in which are given results of studies carried on under this cooperative agreement. In the Mid-Continent fields, the methods used most generally for handling oil-field brines are: (1) Impounding in evaporation ponds; (2) controlled diversion into surface streams; and (3) injection into subsurface formations through wells assigned for this purpose. Various States recognize one or more of the methods as legally authorized procedure. Impounding brine in ponds and solar evaporation have proved inadequate as a general rule, owing, usually, to the porous nature of the soil, the low rate of evaporation, or both. Diversion of

Jan 1, 1937

By J. C. Ion, O. Isaksson, J. Stjernberg

Iron ore pellets are a preferred feedstock for ironmaking. One method used for pelletizing is the grate-kiln process, first established in 1960.During the past decade, the establishment of new grate-kiln plants has increased rapidly, especially in China, and new constructors of pellet plants have started to operate in the market. It is well known that the grate-kiln method yields a superior and more consistent pellet quality compared with the straight-grate process. However, certain issues exist with the grate-kiln plant, which are discussed here, together with proposed practical solutions.

Jan 1, 2015

By R. J. F. Goodfellow

Many underground projects now include preparation of a Risk Register through planning and design as a tool for project and risk management. There is still significant discussion within the industry as to whether and how to best present the Risk Register through the bidding process and the construction phase of a project. While the ITIG Code of Practice for Risk Management of Tunnel Works recommends this approach of continuity in risk management procedures, it is silent on the specifics of how this should be achieved. This paper will explore the perceived benefits and disbenefit of including the project Risk Register with bid documents; format and content that should be transferred and lessons learned using the case history of bidding and early construction phase of the Bi-County Water Tunnel in Montgomery County, MD